I don't believe in HSA. At least not at the homebrew scale. All the research I've done on it seems to indicate that it "could" be a problem at a commercial level where they're pumping barrels of wort through a three or four inch pipe and it's cascading ten feet into a vessel. If what you're...
You could try it, but I suspect you're pretty much stuck with whatever off flavor you have. Most of the compounds that produce off flavors are formed in the first 48 hours of fermentation which is time that things were too warm. What flavors are you tasting?
I'm dreading the day this happens to me, but when it does I'm throwing the whole MFer in a bucket of PBW for two or three days. That stuff will get rid of anything!
Same thing happened to a friend of mine. Like others said,you'll finish high and a bit sweet. FWIW, I brew on a direct fire RIMS (brutus type) system and I heat my strike water to whatever my mash temp is. Sure it will be low when I dough in but it doesn't take long to heat up and I'd rather...
If by aerate the wort you mean shake up what's already in the fermenter, then no. That would be very bad. Check the gravity again in a day or two, it may still be fermenting. Don't start doing stuff until you know what's going on.
-ben